Doom stuff
I love Doom. I first played it in late 1996 or early 1997, when it was introduced to me by a friend not long after our family got our first “modern” computer, a Compaq running Windows 95. The love affair has never faded, and Doom is still my most-played video game to this very day.
Of course, these very days, I don't exactly play Doom the way I used to. While I do still love playing vanilla (thank you Chocolate Doom), most of the time I play with GZDoom, which provides a bunch of enhancements out of the box (high-res, true 3D, dynamic lighting) as well as enabling modding beyond what Doom could originally do with just WAD files.
Here are some of my favorite mods.
DXN Dead Marine (with lighting)
Dead Marine is a fantastic mod for GZDoom. Created by ZDoom forum member Gifty, Dead Marine “aims to add atmosphere, visual pizzazz, and modern punch to Doom without changing any of the gameplay or mechanics.” It adds new monster sounds, environmental sounds, enhanced gore effects, and makes the weapons feel “punchier” without altering their damage output or rate of fire. It's now my preferred way to play Doom (provided I'm playing vanilla Doom or sufficiently vanilla-like addons).
I first learned about Dead Marine through DavidN's YouTube channel, where he uses it in his Doom videos. He made some modifications to Dead Marine to suit his own preferences, including a new HUD. I really liked it, so I adopted his version.
But, because of the new object classes that Dead Marine uses, GZDoom's lighting effects no longer work for most objects in the game. Dynamic lighting is one of my favorite features in GZDoom. So, I added it back. I've never actually done any Doom resource editing (let alone [G]ZDoom), but it was fairly simple to do, just by copying over the lighting definitions from GZDoom's lights.pk3 file and changing the class names.
You can find David's version of Dead Marine here, or download my version with the restored dynamic lighting here.
DamNums
A very simple mod for GZDoom that adds RPG-style popup numbers that tell you how much damage you've done to enemies.
DamNums was created by Xaser. You can get it on the ZDoom forum thread here.
Doomgirl
Another really simple mod: this one, by Skelegant, changes Doomguy into Doomgirl! It replaces your HUD pic, weapon sprites, and sounds.
You can download Skelegant's Doomgirl skins from the forum post here.
Doom Not In Technicolor (DM2PAL)
A quality-of-life mod that fixes the palette in vanilla Doom so that reds and pinks no longer fade to brown in low light. It's compatible with original Doom for DOS, as well as software-rendered source ports like Chocolate Doom and ZDoom.
The version I'm linking here is DVIIPAL, a fork of DM2PAL that improves certain color gradients and restores the automap to its correct colors.